Fire, Ice, and the Oncoming Storm
by Hesychia
Summary: Zuko needed a break; Katara needed an adventure. The Doctor needed more friends before he died. Pre-Impossible Astronaut and Post-Hundred Years War; pairings include Zutara
1. Chapter 1

**A/N: This is my first crossover fic, but rate fairly. As we know, when the Doctor visits Amy and Rory in the Impossible Astronaut, he's gotten two-hundred years older. Amy, Rory, and River travel with him throughout the rest of the series for what, a year? At least, that's my understanding. So what would you do if you were a thousand-year-old timelord with nothing to do? Visit the Fire Nation; duh. ^_^**

Katara rolled over on the silk mat, frowning at the ornate wall. A map covered with red hung there, glaring down and reminding her that they hadn't changed out the décor in this room for years.

It had only been two since that map had been accurate. Two years ago, she never even considered that she would be within the Fire Lord's palace, much less welcomed there as an honored guest.

Katara sat up as she heard footsteps, trotting to the door. She opened it, expecting-

"Oh. Hello, Mai."

"Expecting someone different?" Fire Lord Zuko's fiancé walked past Katara and into the quarters. "I can't believe they gave you this room," she remarked sullenly. "It hasn't been used for years."

"I chose this room," Katara murmured, struggling to keep her voice respectful. Despite the fact that Mai had proven her loyalty to Zuko and the avatar's cause, the waterbender had a hard time trusting her.

"Oh. Why?" Mai sniffed at the burning incense. "It smells like plants in here."

"The incense was a gift from Toph's mother," Katara muttered, fist clenching. "I chose this room because it wasn't too gaudy."

Mai glanced at the map on the wall. "You didn't take this down?"

"It's a reminder."

"Of what? Wasted years of fighting? Your family being torn apart, your mother taken away?"

Katara's blood suddenly felt like ice. "Who told you?" she hissed.

"Zuko, obviously." Mai wandered to a dresser, picking up an earthen figurine. "He tells me everything; he trusts me." She examined the penguin figurine, stating, "A gift from the avatar, huh?" Mai smirked and set it down. "Cute."

Katara clenched her fist; she hadn't seen Aang for months, nor Sokka or Toph. "Have you gotten any word from him?"

Mai glanced at her with dead eyes. "Go ask Zuko, but wait until after his peace meeting." She paused, and then added, "And after he's signed a few new decrees."

Katara sighed. "Forget it." As Mai exited, the waterbender sat down at her desk and watched the earth penguin dully.

"Oh, and Katara?" Mai remarked on her way out. "Don't even think about falling for him."

Katara stood up, furious. Before she could retort, though, Mai closed the doors with a smirk.

The waterbender sat down, muttering obscene things. She might as well have been placed under house arrest when forbidden to talk to Zuko.

For years, Katara had been trying to convince Mai that she wasn't a threat, but the Fire Lord's fiancé still didn't believe her.

Katara chose to think about other things. For one, she missed Aang, Sokka, and Toph. The avatar and her brother had gone to restore the air temples, while Toph had gone to visit her family in Ba Sing Se. Katara had volunteered to stay at the Fire Lord's palace in case of any traitors.

It had been one month; she had never felt more useless.

Katara stood finally, sighing and exiting. She would go to the turtle-duck pond and practice waterbending… again.

**Breakline**

So many worlds, so little time. The Doctor whirled around the console, wondering which one to visit next. "Well, hello!" He frowned at a planet; humans, though they had lost their technology and replaced it with a form of science called… bending.

The Doctor was more than intrigued; he wondered how he'd ever missed such a marvelous planet and pushed a few buttons, pulling a lever, and staring at the screen. "Ooh, a war? Hate wars. A hundred years! Well then! Let's try for a few years after; there's bound to be some interesting people."

Katara suddenly let the water whip fall back into the pond; she looked around, confused at the rippling sound. Or was it a tearing sound?

She turned, screeching and falling back as a large blue box appeared before her. The box towered over her as it became clearer, more substantial.

Suddenly, the door opened and a head poked out. "What a planet!" The man walked out, smiling at her. "Hello! I'm the doctor!"

Katara stared up at the man; he wore the strangest clothes she'd ever seen. His robe reached to his waist, and his hair was light brown. He had a strange knot at the base of his neck, and his pants were stiff and straight.

The Doctor offered his hand to the girl. "Did I knock you over? Sorry about that; I didn't mean to startle you. What's your name, then?"

Katara blinked at this ridiculous person. His hand was still extended to help her; as she stared into his strange, foreign eyes she saw the age and the sadness behind the silliness. Katara took his hand, standing.

"Katara."


	2. Chapter 2

**A/N: This is a pretty long chapter, but I wanted to get the ball rolling. R&R**

"He's not a threat, Zuko."

The Fire Lord glanced at the strange man examining the statue of a dragon. "Katara, he's… weird."

"So? He's harmless."

Suddenly, a loud crashing sound echoed through the hall. The benders whirled around, glaring at the Doctor, who stood over the fallen dragon statue. "Oops!"

Zuko snarled and indicated one of the guards to hold him. The Doctor didn't seem phased by a large firebender grabbing his wrists. "You're all so Asian! Don't suppose you know where Asia is; it's on Earth! Of course, I don't suppose you know where that is either…" He continued chattering nonsense to himself.

"He's insane," Zuko realized.

"Maybe not," Katara reassured him. "He has old eyes, Zuko."

The Fire Lord glared at her. "So we're supposed to treat him like a guest because he has old eyes?"

Suddenly, the door to the main hall opened. Iroh entered, smiling at the Doctor and bowing respectfully. "Release him! He is our guest!"

Zuko stared at his uncle incredulously. "Uncle!"

"This man is no threat; he's not even armed!"

The Doctor smiled and bowed respectfully to Iroh. "Thank you, sir! Now then, let's look around."

Iroh watched the man, fascinated. "What a strange person."

"No kidding," Zuko muttered.

"Let's invite him to dinner!"

Zuko groaned. Katara glanced at the strange man, smiling gently.

**Breakline**

Within the next two weeks, the Doctor visited off and on. He would come for dinner or a festival and then run off to his box; his TARDIS. Katara watched with envy as he disappeared, though he usually appeared the next morning, acting like it had been months.

For example, the next day he returned bubbling with questions about bending, dragging Zuko away from his duties to demonstrate for him. Mai watched from the shadows, eyes narrowed. Katara sat on the steps watching, smiling and glancing at Zuko's fiancé snidely. She wondered if Mai was jealous of the Doctor taking up the firelord's time.

Katara loved to spend time with the Doctor; he was riveted with the Fire Nation's way of life, insisting on trying every food. They would sit in Iroh's tea shop and he would tell her marvelous stories about people far away. He said she was the only waterbender he knew, which surprised her. The Doctor claimed that in other worlds, they didn't bend at all. They used technology; giant tanks and enormous ships that could fly through the stars.

In return, Katara would demonstrate waterbending and occasionally, he would run to the TARDIS, promising a return in minutes and coming back hours or even days later.

Every day, she sat in the garden and practiced new tricks to show him.

Sometimes, after Mai had gone home to her family, Katara would sneak into Zuko's room and sit on his bed, retelling the Doctor's stories, though she could never explain them with such fluency or excitement.

On more than one occasion, he'd fallen asleep as Katara spoke; she felt sorry for him, having so many royal duties. The Doctor was really the only way they could spend time together.

Mai would get more and more suspicious; she considered the Doctor a threat to her perfect world. She struggled to drag Zuko away from his responsibilities with the Fire Nation and budding friendship with the Doctor, wrenching him back into her world to give him a respite from the hardships.

Katara, Zuko, and Mai all knew the truth of the matter, however; what joy, what recreation could Mai provide that the Doctor couldn't?

**Breakline**

One night, the Doctor had come for Iroh's birthday. The party was small, consisting of the Fire Lord, his fiancé, Katara, and a few generals and close acquaintances within the nobility.

Inside Iroh's tea shop, tea was shared and plates of hot dumplings were piled on a table.

The Doctor whirled inside like a rampant tornado, carrying a large, rectangular box. He peeked out from behind it, flashing his addictive smile. "Am I late?"

Iroh, like Katara, had taken an immediate fondness with the Doctor, laughing as he invited him inside. "Punctual as always; would you like some tea?"

"How could I refuse?" the Doctor answered, setting the box down by the other humble presents in a corner.

Mai's eyes narrowed as he entered. "What is he doing here?" she muttered to Zuko, struggling to hide the irritation in her voice.

"He's a friend," Zuko answered, his hair dangling just above his eyes. Mai loved it when he let his hair down, since he had recently gotten a hair cut that ended at his ears.

The festivities began and everyone sang for Iroh; there was great merriment throughout the next hour, as the Doctor stole the show and proved to be a great host of games.

When presents were opened, Iroh was quite pleased; Zuko had bought him a bonsai tree, while Katara had given a small fountain that cycled its water. Mai wasn't very acquainted with Iroh, which was obvious when she gave him a bag of expensive incense. Iroh preferred herbs that he could make tea with, having a terrible allergy to those inside the incense, but he still thanked her.

The Doctor's present came last; Iroh opened it cautiously. The box sides finally fell away, and a stone dragon statue nearly three feet tall was revealed. "To replace the one I broke, or to put in the shop!"

Iroh smiled gratefully at the Doctor. "It's beautiful; I'll put it right here in front."

However, the Doctor wasn't nearly finished. He later brought out a strange dish called cake. He placed it before Iroh, while the others gathered around curiously.

The Doctor proceeded to stick candles in the cake, insisting that Iroh light them. Bewildered, the man did so, dazzled. "It's very… ah…"

"Weird," Mai mumbled.

"Now make a wish and blow out the candles! Without firebending, that is!"

Iroh did so; a few of the guests clapped awkwardly as the Doctor clapped excitedly. "Now we slice it up and eat!"

As the guests dived in somewhat tentatively, Katara looked over at Mai. The girl was sitting at a table near the wall, looking unimpressed and bored. Finally, Katara sliced a piece of cake, walking over to Mai with the plate. "Do you want some?"

Mai glanced at the cake disdainfully. "Thanks, but no thanks."

"Come on; it's really good."

"I said no thanks."

Katara sighed, sitting across from Mai. "Why not? It's just a treat."

"Yeah; an alien treat. Who knows what kind of weird disease it might carry?"

Katara frowned. "The Doctor wouldn't serve us anything dangerous."

"Why do you even trust him?" Mai asked as she examined a spoon. "He's a weird alien from who knows where. He pops up on our doorstep, dresses strange, eats strange foods; he's unreliable, irresponsible, and kind of creepy. How can you even trust someone you barely know?"

Katara searched Mai's dead eyes with wonder. "I could say the same about you; Mai, for months, you were my enemy. But if Zuko trusts you, I trust you." She paused. "Do you think… you could find it in your heart to trust me?"

Mai's eyes met Katara's. They suddenly narrowed menacingly, though her voice was calm. "I don't trust anyone; especially not you. You're just some nobody waterbender kid who thinks she's so great because she helped end a war. We all did our part, so what makes you think you're special? Not to mention how you always want to spend time with Zuko. Understand this, Katara; he's _mine._"

"I know that," Katara answered, fist clenching. "Do you?"

Suddenly, a screech sounded; everyone whirled around to find Mai and Katara sitting across from each other, the plate empty. Mai stared down at her lap, eyes wide with horror. "Katara, why would you even _do _something like that?"

Katara stared at the cake splattered across Mai's clothing with confusion. "What are-"

"Katara! I can't believe you! You don't have to do things like this just because you're jealous!" Mai stood up, annoyed. "Just because you can't have everything I have doesn't mean you have to treat me like this!" Mai whirled around, running out of the room in distress.

Katara stared blankly at the spot Mai had been; suddenly, she stood, running after her into the night. "Mai!" she called down the dark streets.

A pot rattled, and Katara turned into an alley. "Mai?"

A knife pressed to her throat.

"I know a lady is supposed to exit a party with grace, but I thought I could make an exception," Mai purred into Katara's ear. "Don't forget this, water girl; Zuko is mine, and nothing can take him away from me. Not you or your precious Doctor."

Katara winced at the cold blade pressing to her; she didn't dare to speak.

"You know, maybe you're not jealous of me just because of Zuko. You're jealous because of my life; safe, secure, not a care in the world." Mai leaned closer. "Not only that, but my mother's still alive."

Katara growled, and the water from a nearby rain barrel rose out, lashing at Mai. However, the girl leaped back into the shadows, and in an instant, she had disappeared.

Katara stood there for a few moments, annoyed. Finally, she yelled, throwing the water against the alley wall and running.

**Breakline**

The Doctor and Zuko hadn't seen where the girls had gone. The Doctor turned to the Fire Lord, asking, "That was unusual, don't you think? Katara doesn't seem like the jealous type."

"I don't know what came over her," he answered, staring out into the night. "But I know Mai must be telling the truth."

The Doctor watched Zuko curiously. "You're lying."

"That's what people do." Zuko trotted into the night.

The Doctor sighed, running after him.

**Breakline**

Katara sat beside the TARDIS; the night was cold, but the box was always miraculously warm, as if burning with life. The waterbender sniffed and leaned her head against the blue box, and it seemed to react as if trying to comfort her.

"Katara?"

She looked up as Zuko trotted over, wiping away her tears hastily. "Zuko, I didn't do it; Mai framed me."

"I know." He paused. "What did she say, Katara?"

"What do you mean?"

"You're crying; you're not the person who cries over spilt cake."

Katara hesitated, and then murmured, "She… thought I was jealous because her mother is still alive…"

The TARDIS shuddered as Zuko punched it. He took a deep breath, turning to her. "I'm sorry, Katara. I'll have a talk with her."

"What, so you can tell her more of my secrets? Secrets I told you because I thought I could trust you?" Her voice was rising; Zuko stepped back. "Why would you tell her that, Zuko? Didn't you know she could use it against me? Haven't you noticed what a jealous, conniving, paranoid, rich pig she is?"

Zuko froze, staring into Katara's furious blue eyes. He took a deep breath. "No. I've been busy; I thought you two were bonding."

"She _forbade _me from seeing you! One of my best friends! You didn't even try to include me in your meetings, your duties! After all we've been through; after we helped you find your mother!" Her voice cracked on the last line.

"That wasn't my choice! I wanted you there; I thought I was giving you a vacation! I didn't realize any of that, because while you were stuck in outside the walls, I was inside working my toes off!"

Suddenly, the TARDIS doors opened beside them; the benders jumped back in surprise, turning to see the Doctor standing there with a grin on his face. "Sounds like you two need a doctor."


	3. Chapter 3

**A/N: Let's get a little adventurous. R&R**

Katara's feet flew, her heart pounding to the sound of the drums. "I hate Earth," she muttered, leaping over a bush and into a river. She dove through the water, bending it to send her up into the air. She turned, taking a deep breath and staring up at the barbaric hunters perched on the bank.

A hand grabbed her; Katara yelped as she was hoisted out of the water. "Calm down," a familiar voice murmured. The waterbender stopped, gasping.

Zuko let her go, and Katara took a deep breath. "Where's the Doctor?"

"Here, Katara!" The Doctor poked his head out of a tree; the shift in his weight suddenly caused the branch he was sitting on to snap. He yelped as he fell to the ground, rolling out of the way as the TARDIS landed heavily where he had fallen.

The Doctor coughed, standing up. "That's new; never crashed in a tree before. No matter; we should be up and running soon enough!"

Katara and Zuko exchanged looks. The waterbender replied, "You better hurry up, because the savages are on their way!"

"Completely my fault, you know; I planned on visiting Asia a little more in the future but it appears we arrived a little early. Well, no harm done!"

Katara was about to give him a piece of her mind, but she coughed as the barbarians yelled from a few hundred yards away. "Doctor!" Zuko yelled angrily.

The Doctor snapped his fingers; the TARDIS doors opened and they ushered Katara inside as the barbarians poured from the trees and bushes, charging at the TARDIS.

There was a tearing sound; the doors closed and the box was rushing through the time vortex again.

"Well then," the Doctor said after a moment of silence. "Where to next? Somewhere hot? Somewhere cold? Ooh! Have you ever heard of Terraphota? The planet literally glows! Even the water! Wonderful vacation spot!"

Katara and Zuko exchanged glances as the Doctor chattered. "I'm going to take a bath," Katara announced.

"I'll heat the water," Zuko added.

Zuko took a deep breath, lighting a fire beneath the tub full of water. Katara watched from the doorway.

When the Doctor had appeared that night, everything had happened so fast. The benders were about to attack him. Suddenly, Mai's voice carrying through the garden had scared them into the TARDIS.

With a twirl and a shudder beneath them, the trio had been flung into the time vortex. Zuko and Katara had been strangely silent, staring at the mysterious and alien world around them.

The benders had grown accustomed to the Doctor's strange ways, but nothing prepared them for this. Finally, after they had been given a sufficient amount of time for discovery, the Doctor asked where they wanted to go.

"Earth," Zuko had answered immediately. "The parallel world you keep telling us about."

"Ah, the birthplace of humanity; wonderful!" A few buttons, a lever, and some strange knob that made a whistling sound when he pulled it out; they were off.

Even the encounter with the barbarians had moved too quickly; now that everything had slowed down, Katara could think.

"We ran away," she murmured.

Zuko was still kneeling by the tub of water. "Yeah."

"With the Doctor."

"Mmhmm."

"We left everyone we love at home and we ran away."

"No."

She watched him as the fire lord stood, eyes downcast. Suddenly, he looked up at her, meeting her blue eyes with his fierce gold ones. To her surprise, those eyes were shining with happiness. "We're traveling through time and space; we just visited another planet and got chased by people who died millions of years ago." A smile hovered on his lips. "Don't you get it? We didn't run away; we escaped."

They stood there in silence; Katara stared at the floor. She glanced up, meeting his elated eyes. A grin suddenly played on her lips, and then stuck there. The grin grew and grew until she was smiling, and she ran forward and wrapped her arms around him, embracing him tightly.

The Doctor watched on one of his screens; he smiled, pulling out a washrag and wiping down the console, murmuring, "I'm never going to learn, am I? I might as well have a few more friends before I…" The Doctor paused, looking up at the screen that displayed the date.


End file.
